As an example of such installations, container-closure installations are known that comprise a rotary platform with a periphery fitted with spindles for screwing on stoppers and with means for supporting containers under the screw-fastening spindles. A container feed star and a star for removing closed containers are provided adjacent to the platform, both stars being rotary and fitted at their peripheries with container-support means.
In general, a liquid-packaging production line has a plurality of installations disposed one after another and comprising in particular a filler installation, a closure installation, and possibly an installation for washing or rinsing containers, an installation for sterilizing them, . . . .
The rates of throughout of such installations give rise to relatively high container travel speeds. It is therefore necessary to hold containers to the stars and the platforms sufficiently securely to ensure that containers do not fall off.
In addition, certain operations, such as closing by screwing on a stopper, cannot be performed without the containers being prevented from turning about the screw-fastening axis. With containers made of plastics material, it is possible to prevent such containers from turning by means of sharp blades or spikes that bite into the material of the container, in particular beneath the collars of containers when the containers are supported by their collars. It is then necessary to exert a vertical force on the stoppers while they are being screwed on so as to enable the blades or spikes to penetrate into the collars. This force gives rise to an interfering opposing torque that makes it difficult to obtain a predetermined level of tightening torque for the stoppers. Furthermore, prior to the blades or spikes achieving penetration, the containers tend to turn so that the collars of the containers tend to rub against the blades or spikes, which then detach shavings that become dispersed within the installation. Neck-retaining devices might be devised for preventing such rotation.
Nevertheless, holding the containers firmly must not impede transferring the containers between the stars and the platforms. Such transfers of containers from one apparatus to another constitute operations that are critical during which the movement of the containers, and they need to be opposed as little as possible so as to avoid any containers being poorly positioned on said apparatuses.